Electron donor compounds can maximally change the property of the active center of Ziegler-Natta catalysts for olefin polymerization, thereby changing the performance of the catalyst to the greatest extent. Therefore, in a sense, research on high-efficiency Ziegler-Natta catalyst is to find better electron donors. The research on the internal electron donor in China and abroad is mainly focused on traditional fatty acid esters and aromatic acid ester compounds; diethers (e.g. EP0361493, EP0728724) and succinic acid esters (e.g. WO9856834, WO0063261, WO03022894) compounds; and diol esters (e.g. CN1580033, CN1580034, CN1580035) compounds, etc. However, in practical applications, there are some problems with the aforementioned compounds serving as the electron donor of catalyst component for olefin polymerization, e.g. the polymers obtained by use of the catalyst system prepared by diether compounds have a narrow molecular weight distribution, while the polymer products obtained by use of the succinic acid ester catalyst system have a broad molecular weight distribution. The activity of diol esters catalyst system is often not as good as that of diether system. In order to obtain a more balanced overall performance of the catalyst, a variety of new compounds have been developed and used in the preparation of Ziegler-Natta catalysts.
Introduction of more functional groups into a compound structure is one of the general trend in creating the electron donor compounds with excellent overall performance. There are many reports on the preparation and application of the polyfunctional compounds, such as the development of new internal electron donor, such as keto-ether (WO2010144079), keto-ester (WO2005097841), and ether-ester (WO2005123784, WO2012087522, WO2012087527). The main purpose of introducing multiple functional groups in a compound is to take full use of the advantages of these functional groups.
However, Ziegler-Natta catalyst components prepared by using the aforementioned compounds are still unsatisfactory in activity/isotacticity when used for olefin polymerization, therefore further research and development are still required.